1. Field of the Invention
This invention relates to high-strength oil-tempered steel wire with excellent spring fabrication property, high fatigue strength and low setting property that is suitable for use in vehicle internal combustion engines, suspensions systems and the like and to a method for producing the same.
2. Description of the Prior Art
Springs used in the internal combustion engines, suspension systems etc. of vehicles and the like are being reduced in size in response to the trend toward higher horse-power. This has lead to the development of more sophisticated spring materials in recent years as well as to the development of spring materials added with Mo and/or V to improve temper softening resistance.
While these spring materials improve spring fatigue strength, they make spring fabrication difficult. Even when minute surface defects that do not become fatigue starting points during use are present, they may cause breakage during spring fabrication, which makes it difficult to produce springs of uniform quality.